是什么调用和BeginInvoking一个MessageBox之间的区别？ [英] What is the difference between Invoking and BeginInvoking a MessageBox?

问题描述

在一个表格，比较

BeginInvoke (new Action (() => {
    MessageBox.Show ());
}));

与

with

Invoke (new Action (() => {
    MessageBox.Show ());
}));

的区别是什么，当我应该使用一个比其他？如何受的MessageBox的消息泵的行为？

What is the difference, and when should I use one over the other? How is the behavior affected by the message pump of the MessageBox?

我做了一些测试，发现的两个方法阻止用户界面。

I did some testing and found that both methods block the UI.

唯一的区别是，调用实际上是瞬间称为一段时间，直到代码运行的BeginInvoke需要（很短）的时间。这是可以预料的。

The only difference is that Invoke is actually called instantly while BeginInvoke takes a (very short) time until the code is run. This is to be expected.

推荐答案

的 的BeginInvoke 将异步调用该委托，独立有排队的执行委托立即返回当前线程。

BeginInvoke will invoke the delegate asynchronously, returning immediately having queued the delegate for execution independently of the current thread.

的 调用 将同步调用委托，到委托完成阻塞调用线程。

Invoke will invoke the delegate synchronously, blocking the calling thread until the delegate completes.

要看到其中的差别，试试下面的代码：

To see the difference, try the following code:

BeginInvoke(new Action(()=>Console.WriteLine("BeginInvoke")));
Console.WriteLine("AfterBeginInvokeCalled");

Invoke(new Action(()=>Console.WriteLine("Invoke")));
Console.WriteLine("AfterInvokeCalled");

您应该看到类似以下，其中BeginInvoke的文本由于延迟到它的异步输出执行：

You should see output similar to the following, where the "BeginInvoke" text is delayed due to its asynchronous execution:

AfterBeginInvokeCalled结果
调用结果
AfterInvokeCalled结果
的BeginInvoke

AfterBeginInvokeCalled
Invoke
AfterInvokeCalled
BeginInvoke

对于你观察到的，因为它仅仅是调用的委托，为同步或异步的行为的行为;该方法的内容很可能导致调用线程停止或用户界面被阻塞。在示出的消息框，无论代表是否使用的 的BeginInvoke 与否，一旦委托被调用时，用户界面​​将会被阻塞，直到消息框被驳回。

Regarding the behaviour you observe, as it is only the act of calling the delegate that is synchronous or asynchronous; the content of the method may well cause the calling thread to stop or the UI to be blocked. In the case of showing a message box, regardless of whether the delegate is delayed using BeginInvoke or not, once the delegate is called, the UI will be blocked until the message box is dismissed.

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